The present invention relates to digital image processing systems and processes for quantitative particle characterization and, more particularly, to a system and a process for automatic characterization of palynological and sedimentological samples based on algorithms implementing techniques of image enhancement, connectivity and morphological analysis, operating on the objects or patterns in an input image obtained by means of a TV camera.
Textural description of organic matter particles by size and shape has previously been performed by direct measurement of each particle using a visual scale through a viewing device, usually a microscope, for quantitative data, and by comparison with visual charts for qualitative data.
Pore size determinations and rock mineral analysis has traditionally been done either by counting unit areas (point counting) with a mechanical device or by manual planimetry of a projected image.
These measurement methods have the disadvantage of being very subjective to operator opinion and are also very time consuming.
Early techniques for the quantitative characterization of organic remains were first mentioned in the literature by M. A. Lorente in a paper entitled PALYNOLOGY AND PALYNOFACIES OF THE UPPER TERTIARY IN VENEZUELA. The paper discussed some basic concepts for transforming the raw data on observed organic matter particles as obtained by a QUANTIMET device into geologically meaningful parameters.
The patent literature is characterized by several patents in the field of particle analysis.
U.S. Pat. No. 4,229,797 describes a method and system for whole picture image processing, in particular for automatic measurement of texture and color by an electronic device, whereby certain parameters are obtained by effective electronic subtraction of an original first image from a "smoothed" (locally averaged) second image to obtain local maxima, which points are further used to calculate first, second and third moments of objects as parameters that could be compared with tables or predetermined standard patterns of texture representing known classifications of medical objects.
UK patent application Ser. No. 2,029,570-A, describes a method and apparatus for image analysis and automatic classification of a field of objects that uses interaction with an operator to select a threshold image intensity value to distinguish a set of objects in the field of view, considered by the operator as belonging to a particular class of objects, from all other such objects. Automatic measurement and storage of the threshold value and other computed parameters describing the selected objects permits the device to later classify objects in other images as belonging to a previously described class. This published patent application specifically refers to a QUANTIMET image analyzer device intended to be used to measure total porosity and to quantify shape, size distribution and connectivity of pores for quantifying grain shape in soils and sediments. This invention has the disadvantage of requiring a device of great complexity and consequent high cost, whose nature is fixed and therefore inflexible. It also relies on the judgement of an operator to calibrate the classification system. Further disadvantages of the noted complexity are the consequent high cost and the relative untransportability to remote operating areas in the geological sciences.
U.S. Pat. No. 4,700,298 describes a microscope image processing scanner for locating, measuring and recognizing live cells growing in tissue culture flasks. The main objective of the invention is to locate, identify and track moving cells in a dynamic environment. The described technique is limited to determining the presence and location of a cell in two dimensions within the field of view. Measurements of image density are used to identify cells from debris and other inconsequential objects. No form or shape parameters are extracted.
Generally, these systems are not suitable for use in the quantitative characterization of organic matter concentrates and of petrographic thin sections or polished fragments of rock found in oil reservoir samples.
Accordingly, it is an object of the present invention to provide a system and process for use in the quantitative characterization of organic matter concentrates and of petrographic thin sections or polished fragments of rock found in oil reservoir samples.
It is a further object of the present invention to provide a system and process as above which obtains morphological data about samples using image digital analysis techniques.
These and other objects and advantages of the present invention will become more apparent from the following description and drawings in which like reference numerals depict like elements.